If the abstract class does not provides any methods, it may be just a data container that is not to be instantiated. In this case, it's probably better to use a private or a protected constructor in order to prevent instantiation than make the class misleadingly abstract. Example :
<pre>
public class abstract Example {
  String field;
  int otherField;
}
</pre>

<p>
 This rule is deprecated, use {rule:squid:S1694} instead.
</p>
